Detent mechanism for brake booster

ABSTRACT

A hydraulic brake booster is disclosed which includes a housing, a piston slidable in the housing and operatively connected to a master cylinder for actuating the latter, and valve means for admitting pressurized fluid into the housing for shifting the piston. A sleeve is slidably mounted on an operator-operated control rod that is slidably mounted in the housing, ans a pair of levers pivotally interconnect the piston, the sleeve, and the valve mechanism. A releasable coupling device joins the sleeve to the rod for movement therewith when the valve mechanism is functioning normally, but permits the rod to move relative to the sleeve when a malfunction prevents movement of the valve means.

United States Patent Boyer Mar. 7, 1972 [54] DETENT MECHANISM FOR BRAKEPrimary ExaminerEdgar W. Geoghegan BOOSTER Assistant Examiner-Irwin C.Cohen Attorney-W. N. Antonis and Plante, Arens, Hartz, Smith andThompson i 57 ABSTRACT 3 ing, a piston slidable in the housing andoperatively connected to a master cylinder for actuating the latter, andvalve means 1 for admitting pressurized fluid into the housing forshifting the piston. A sleeve is slidably mounted on anoperator-operated control rod that is slidably mounted in the housing,ans a pair of levers pivotally interconnect the piston, the sleeve, andthe valve mechanism. A releasable coupling device joins the 1 sleeve tothe rod for movement therewith when the valve 1 mechanism is functioningnormally, but permits the rod to 1 move relative to the sleeve when amalfunction prevents movement of the valve means.

7Claims,4DrawingFigures [72] Inventor: Peter W. Boyer, South Bend, Ind.

[73] Assignee: The Bendix Corporation [22] Filed: Mar. 16, 1970 [21]Appl. No.: 19,579

[52] US. Cl. .L ..9l/391 [58] FieldofSeai-ch ..9l/39l,377, 378,418

[56] References Cited UNITED STATES PATENTS 2,597,418 5/1952 Westbury etal. ..9l/391 X 2,766,732 10/1956 Schultz ....91/384 X 2,934,042 4/1960Stelzer..... ....9I/377 X 2,976,849 3/1961 Stelzer ..9l/391 X FOREIGNPATENTS OR APPLICATIONS 1,105,351 3/1968 cm; Britain ......I.....I173iDETENT MECHANISM FOR BRAKE BOOSTER BACKGROUND OF THE INVENTION Thisinvention relates to a hydraulic boost device for use in the brakesystem of an automotive vehicle.

Because of their smaller size and lower weight, hydraulic brake boostersare expected to be used in lieu of vacuum boosters in vehicles havingpower assisted brakes in the near future. Such a device is disclosed inU.S. patent application Ser. No. 793,923, filed .Ian. 16, 1969, owned bythe assignee of the present invention and incorporated herein byreference. This unit utilizes the pressurized fluid produced by thevehicles power steering pump to provide a hydraulic assit to the vehicleoperator when the brakes are applied. The device disclosed in theaforementioned application permits manual actuation of the brakes shouldthe supply of pressurized fluid to the unit be terminated or should amalfunction in the valve mechanism fail to communicate fluid into theunit. After an initial malfunction, the valve sometimes resumes normaloperation after the brakes have been partially applied manually. Whenthis occurs, the vehicle stops abruptly, often damaging the vehicle andinjuring its passengers.

SUMMARY OF THE INVENTION Therefore, an important object of my inventionis to prevent the valve mechanism from admitting fluid into a brakebooster after an initial valve malfunction has initiated manualactuation of the brakes.

Another important object of my invention is to provide coupling meansthat automatically disconnects the operatoroperated control rod from thevalve actuating mechanism of the brake booster when a valve malfunctionhas initiated a manual brake application.

A further object of my invention is to provide a coupling means thatautomatically disconnects the operator-operated control rod from thevalve actuating mechanism when the valve malfunctions, but whichautomatically recouples the control rod to the valve actuating mechanismwhen the brakes are released to permit normal operation of the brakebooster if the valve mechanism functions normally on future brakeactuations.

DESCRIPTION OF THE DRAWINGS FIG. I is a schematic view of a vehiclehydraulic system with a brake booster made pursuant to the teachings ofmy present invention illustrated in cross section;

FIG. 2 is an enlarged, fragmentary, cross-sectional detail view of thecoupling mechanism used in the brake booster illustrated in FIG. 1;

FIG. 3 is an enlarged, fragmentary, cross-sectional detail view, similarto FIG. 2, but illustrating the position of the various elements of thecoupling mechanism while the latter is releasing; and

FIG. 4 is an enlarged, fragmentary, cross-sectional, detail view,similar to FIGS. 2 and 3, but illustrating the position of the variouselements of the coupling mechanism after the latter has released.

DETAILED DESCRIPTION Referring now to the drawings, a brake boosterincludes a housing 12 having an inlet port 14, an outlet port 16, and areturn or exhaust port 18. The inlet port 14 is communicated with thehigh pressure side of a power steering pump 20, and the outlet port 16is communicated with the inlet of a power steering gear 22. The exhaustport 18 is communicated to the low pressure side of the pump 20 as isthe outlet port of the power steering gear 22.

A piston 24 is slidable in a longitudinally extending bore 26 within thehousing 12. One end of the piston 24 is slidably received in a boostchamber 28 within the housing 12. A rod 30 connects the other end of thepiston 24 with a standard master cylinder (not shown) mounted on theleft side of the housing 12 viewing FIG. 1. Movement of the piston 24 tothe left develops pressure in the master cylinder in the usual manner toapply the vehicles brakes. A return spring 32 also engages the other endof the piston 24 to return the latter to its normal position after thebrakes are released.

A spool valve 34 is slidable in a bore 36 within the housing 12 and isadapted to control fluid communication between the inlet 14, the outlet16, and the boost chamber 28. In the position illustrated in FIG. 1, thespool valve 34 communicates substantially all of the fluid that flowsinto the inlet directly to the outlet, and vents the chamber 28 to thelow pressure side of the pump 20 through the exhaust port 18. When thevehicle operator depresses the brake pedal, spool valve 34 is shifted tothe left viewing FIG. 1, terminating fluid communication between thechamber 28 and the exhaust port 18, and simultaneously directing aportion of the fluid flowing into the inlet l4 through radiallyextending passages 38 and longitudinally extending passages 40 in thespool valve 34. Details of the construction and operation of the spoolvalve 34 are described in copending US. patent application Ser. No.l3,4l5, filed Feb. 24, 1970, owned by the assignee of the presentinvention and incorporated herein by reference.

An operator-operated control rod 42 is slidably mounted in yet anotherbore 44 within the housing 12. One end of the control rod 42 is securedto the usual brake pedal (not shown) in the vehicle operatorscompartment and the other end of the rod 42 is slidably supported in ablind bore 46 formed in the end of the piston 24. A circumferentiallyextending groove 48 is formed in the rod 42 and is adapted to receive aplurality of force-transmitting elements or spheres S0 spacedcircumferentially around the control rod 42. A second groove 52 having asubstantially greater axial length than that of the groove 48 is alsoformed in the rod 42, and is separated from the groove 48 by a ridge 54.A conical spring 56 is disposed between the piston 24 and a snapring 58on the rod 42 and yieldably biases the control rod 42 toward the rightviewing FIG. 1.

A sleeve 60 is slidably mounted on the control rod 42 and has asubstantially greater inside diameter than the diameter of the rod 42. Apair of inwardly projecting abutments 62, 64 are provided on oppositeends of the sleeve 60 and slidably engage the control rod 42. Theabutment 62 is normally disposed between the snapring 58 and the forwardedge of the groove 48 and is provided with a sloping surface 66 thatengages one side of the force-transmitting elements or spheres 50. Aresilient member 68 is disposed between the other abutment 64 and awasher 70, the outside diameter of which slidably engages the insidediameter of the sleeve 60. The resilient member 68 yieldably biases thesloping forward surface 69 of the washer 70 into engagement with theother side of the spheres 50. Access openings 72 are provided throughthe sleeve 60 so that the spheres 50 may be placed in the groove 48.

One end of a pair of levers 74 are connected by pivots 76 to a bracket78 mounted on the piston 24. The other ends of the levers 74 arepivotally connected to the spool valve 34 as at 80. A pin 82 on thesleeve 60 engages slots 84 on the levers 74, providing a pivotalconnection between the levers and the sleeve. The levers 74 aredisclosed in detail in copending US. patent application Ser. No. 35,800,filed May 8, 1970, owned by the assignee of the present invention andincorporated herein by reference.

MODE OF OPERATION In operation, the spring 68 acting through the washer70 normally forces the spheres 50 against the sloping face 66 of theabutment 62 and against the forward edge of the groove 48, therebylocking the sleeve 60 to the control rod 42 for movement therewith. Whenthe brakes are applied, the rod 42, and therefore the sleeve 60, areforced to the left viewing FIG. 1. Movement of the sleeve 60, actingthrough the levers 74, shifts the spool valve 34 to a position admittingfluid into the chamber 28 where it acts against the end of the piston 24to assist the vehicle operator in applying the vehicles brakes. When thebrakes are released, the springs 32 and 56 return the piston 24, the rod42, and the spool valve 34 to the brake release position.

Although the brake booster normally performs quite satisfactorily, anoccassional malfunction sometimes prevents movement of the spool valve34, thereby requiring that the brakes be applied manually. If the spoolvalve 34 suddenly shifts after initiation of a manual brake application,fluid is suddenly admitted to the chamber 28, stopping the vehicle veryabruptly, often damaging the vehicle and injuring the occupants. It is,therefore, desirable that the spool valve 34 be kept from moving after amanual brake application is initiated.

When a malfunction prevents movement of the valve 34, the sleeve 60cannot move, since the sleeve and the valve are connected by the rigidlevers 74. When the vehicle operator depresses the brake pedal forcingthe rod 42 to the left viewing FIG. I, the surface 66 on the abutment 62forces the spheres 50 out of the groove 48 against the bias of thespring 68. Further movement of the rod 42 forces the sphere 50 acrossthe ridge 54, as illustrated in FIG. 3, and into the groove 52, as shownin FIG. 4. Since the groove 52 is slightly deeper than the groove 68,the sphere 50 cannot be wedged between the surfaces 66 and 69 while thesphere is disposed in the groove 52, thereby permitting relative slidingmotion between the rod and the sleeve for a distance equal to the axiallength of the groove 52. This distance is sufficient to permit the endof the rod 42 to engage the end of the blind bore 46 to establish amechanical link between the brake pedal and the master cylinder topermit manual actuation of the vehicles brakes. When the brakes arereleased, the spring 56 urges the rod 42 to the right viewing FIG. 1.Since the spring constant of the resilient means 68 is greater than thatof the spring 56, the washer 70 does not move as the spring 56 forcesthe control rod 42 toward the brake release position. Therefore, thewasher 70 will force the spheres 50 over the ridge 54 and into thegroove 48 as the rod 42 is moved to the right viewing the figures. Thisconstruction insures that if the malfunction in the spool valve 34terminates on future brake applications, therefore permitting the spoolvalve 34 to slide, the rod 42 will be connected to the levers 74 so thatthe booster 10 will function normally.

lclaim:

1. In a hydraulic boost device for a vehicle:

a housing having an inlet, an outlet, a bore communicating the inletwith the outlet, and a chamber in fluid communication with said inlet;

a piston shiftable in said chamber;

valve means shiftable in said bore for controlling fluid communicationbetween the inlet, the outlet, and the chamber; and

operator-operated control means for actuating said valve means;

said control means including a pair of members;

actuating means operably connecting one of said members to the valvemeans, to permit movement of said one member to shift the valve meansfrom a first position in which said valve means communicatessubstantially all of the fluid flowing into the inlet to the outlet to asecond position in which said valve means communicates at least aportion of the fluid flowing into the inlet to the chamber, the othermember being arranged for actuation by the vehicle operator, andreleasable coupling means normally connecting said one member with theother member, but automatically permitting relative movementtherebetween when a malfunction prevents said valve means from shifting;

said one member including a sleeve slidable on said other member, saidactuating means including lever means pivotally connecting the piston,the sleeve, and the valve means;

said other member being a rod having a circumferentially extendinggroove formed therein;

said coupling means including force transmitting elements in said grooveoperably connecting said sleeve to the rod for movement therewith whenthe valve means is functioning normally, but permitting the rod to moverelative to the sleeve when a malfunction prevents movement of the valvemeans.

2. In a hydraulic boost device for a vehicle:

a housing having an inlet, an outlet, a bore communicating the inletwith the outlet, and a chamber in fluid communication with said inlet;

a piston shiftable in said chamber;

valve means shiftable in said bore for controlling fluid communicationbetween the inlet, the outlet, and the chamber; and

operator-operated control means for actuating said valve means;

said control means including a pair of members;

actuating means operably connecting one of said members to the valvemeans, to permit movement of said one member to shift the valve meansfrom a first position in which said valve means communicatesubstantially all of the fluid flowing into the inlet to the outlet to asecond position in which said valve means communicates at least aportion of the fluid flowing into the inlet to the chamber, the othermember being arranged for actuation by the vehicle operator, andreleasable coupling means normally connecting said one member with theother member, but automatically permitting relative movementtherebetween when a malfunction prevents said valve means from shifting;

said one member including a sleeve slidable on said other member, saidactuating means including lever means pivotally connecting the piston,the sleeve, and the valve means;

said other member being a rod having first and second circumferentiallyextending grooves formed therein presenting a ridge therebetween;

said coupling means including force-transmitting elements, and resilientmeans maintaining said force-transmitting elements in said first grooveand in engagement with said sleeve when the valve means is functioningnormally;

said resilient means yielding when a malfunction prevents said valvemeans from shifting to force the force-transmitting element across saidridge into said second groove.

3. The invention of claim 1:

said second groove having a substantially greater axial length than saidfirst groove;

said force-transmitting elements sliding in said groove to permitrelative movement between the rod and the sleeve.

4. The invention of claim 1:

said sleeve having a substantially greater inside diameter than theoutside diameter of said rod;

radially inwardly projecting abutment means on said sleeve slidablyengaging said rod on one side of said groove when said valve meansfunctions normally;

said abutment means engaging said force-transmitting elements; and

resilient means operably connecting to the other side of said elements;

said abutment means urging said elements across said ridge against thebias of the resilient means when said malfunction prevents said sleevefrom moving with the control rod.

5. The invention of claim 4; and

a washer slidably engaging the inside diameter of said sleeve;

one side of said washer engaging said other side of said elemerits;

said resilient means engaging the other side of said washer.

6. The invention of claim 5; and

spring means yieldably biasing said control rod toward the brake releaseposition;

said resilient means preventing relative axial movement between saidelements and said sleeve as said spring means returns said rod to thebrake release position after relative movement between the rod and thesleeve during application of the brakes whereby said force-transmittingelements are forced over said ridge into said first groove.

7. In a hydraulic boost device:

a housing having an inlet, an outlet, a bore communicating the inlet andthe outlet, and a chamber in fluid communication with said inlet;

a piston shiftable in said chamber;

valve means shiftable in said bore for controlling fluid communicationbetween the inlet, the outlet, and the chamber;

an operator-operated control rod movable in said housing;

a sleeve slidable on said control rod;

lever means pivotally interconnecting the sleeve, the piston and thevalve means;

coupling means releasably connecting said sleeve to said rod to permitthe rod to shift said valve means to a position communicating fluid fromthe inlet to the chamber to shift the piston;

said coupling means automatically permitting relative movement betweenthe rod and the sleeve when a malfunction prevents said valve means frommoving; and

spring means engaging said rod for returning said rod and said sleeve tothe brake release position.

1. In a hydraulic boost device for a vehicle: a housing having an inlet,an outlet, a bore communicating the inlet with the outlet, and a chamberin fluid communication with said inlet; a piston shiftable in saidchamber; valve means shiftable in said bore for controlling fluidcommunication between the inlet, the outlet, and the chamber; andoperator-opeRated control means for actuating said valve means; saidcontrol means including a pair of members; actuating means operablyconnecting one of said members to the valve means, to permit movement ofsaid one member to shift the valve means from a first position in whichsaid valve means communicates substantially all of the fluid flowinginto the inlet to the outlet to a second position in which said valvemeans communicates at least a portion of the fluid flowing into theinlet to the chamber, the other member being arranged for actuation bythe vehicle operator, and releasable coupling means normally connectingsaid one member with the other member, but automatically permittingrelative movement therebetween when a malfunction prevents said valvemeans from shifting; said one member including a sleeve slidable on saidother member, said actuating means including lever means pivotallyconnecting the piston, the sleeve, and the valve means; said othermember being a rod having a circumferentially extending groove formedtherein; said coupling means including force transmitting elements insaid groove operably connecting said sleeve to the rod for movementtherewith when the valve means is functioning normally, but permittingthe rod to move relative to the sleeve when a malfunction preventsmovement of the valve means.
 2. In a hydraulic boost device for avehicle: a housing having an inlet, an outlet, a bore communicating theinlet with the outlet, and a chamber in fluid communication with saidinlet; a piston shiftable in said chamber; valve means shiftable in saidbore for controlling fluid communication between the inlet, the outlet,and the chamber; and operator-operated control means for actuating saidvalve means; said control means including a pair of members; actuatingmeans operably connecting one of said members to the valve means, topermit movement of said one member to shift the valve means from a firstposition in which said valve means communicate substantially all of thefluid flowing into the inlet to the outlet to a second position in whichsaid valve means communicates at least a portion of the fluid flowinginto the inlet to the chamber, the other member being arranged foractuation by the vehicle operator, and releasable coupling meansnormally connecting said one member with the other member, butautomatically permitting relative movement therebetween when amalfunction prevents said valve means from shifting; said one memberincluding a sleeve slidable on said other member, said actuating meansincluding lever means pivotally connecting the piston, the sleeve, andthe valve means; said other member being a rod having first and secondcircumferentially extending grooves formed therein presenting a ridgetherebetween; said coupling means including force-transmitting elements,and resilient means maintaining said force-transmitting elements in saidfirst groove and in engagement with said sleeve when the valve means isfunctioning normally; said resilient means yielding when a malfunctionprevents said valve means from shifting to force the force-transmittingelement across said ridge into said second groove.
 3. The invention ofclaim 1: said second groove having a substantially greater axial lengththan said first groove; said force-transmitting elements sliding in saidgroove to permit relative movement between the rod and the sleeve. 4.The invention of claim 1: said sleeve having a substantially greaterinside diameter than the outside diameter of said rod; radially inwardlyprojecting abutment means on said sleeve slidably engaging said rod onone side of said groove when said valve means functions normally; saidabutment means engaging said force-transmitting elements; and resilientmeans operably connecting to the other side of said elements; saidabutment means urging said elements across said ridge against the biasof the resIlient means when said malfunction prevents said sleeve frommoving with the control rod.
 5. The invention of claim 4; and a washerslidably engaging the inside diameter of said sleeve; one side of saidwasher engaging said other side of said elements; said resilient meansengaging the other side of said washer.
 6. The invention of claim 5; andspring means yieldably biasing said control rod toward the brake releaseposition; said resilient means preventing relative axial movementbetween said elements and said sleeve as said spring means returns saidrod to the brake release position after relative movement between therod and the sleeve during application of the brakes whereby saidforce-transmitting elements are forced over said ridge into said firstgroove.
 7. In a hydraulic boost device: a housing having an inlet, anoutlet, a bore communicating the inlet and the outlet, and a chamber influid communication with said inlet; a piston shiftable in said chamber;valve means shiftable in said bore for controlling fluid communicationbetween the inlet, the outlet, and the chamber; an operator-operatedcontrol rod movable in said housing; a sleeve slidable on said controlrod; lever means pivotally interconnecting the sleeve, the piston andthe valve means; coupling means releasably connecting said sleeve tosaid rod to permit the rod to shift said valve means to a positioncommunicating fluid from the inlet to the chamber to shift the piston;said coupling means automatically permitting relative movement betweenthe rod and the sleeve when a malfunction prevents said valve means frommoving; and spring means engaging said rod for returning said rod andsaid sleeve to the brake release position.